To avoid lag from procedures that hog the CPU for too long, you can turn on background processing. This will cause it to periodically sleep for long enough to allow other events to be processed.

The following example is a typical "ticker" procedure. It spawns off an infinite loop which does some work and then sleeps before iterating again. By running this in the background, you ensure that the work being done does not create large delays. You could achieve a similar thing by sprinkling calls to sleep(0) or sleep(-1) in the "working" part of the loop.